Patent Application
20120227688
The present disclosure relates to engine assemblies including variable valve lift arrangements.
This section provides background information related to the present disclosure which is not necessarily prior art.
Internal combustion engines may combust a mixture of air and fuel in cylinders and thereby produce drive torque. Combustion of the air-fuel mixture produces exhaust gases. Valve lift mechanisms may control opening and closing of intake and exhaust valves to control air flow to the combustion chamber and exhaust flow from the combustion chamber. Variable valve timing mechanisms may be used to adjust the opening and/or closing of intake and/or exhaust valves.
An engine assembly may include an engine block, a cylinder head assembly, a first valve, a second valve, a first valve lift mechanism, a second valve lift mechanism and a camshaft. The engine block may define a first cylinder and a second cylinder. The cylinder head assembly may include a first member coupled to the engine block and a second member coupled to the first member.
The first member may define a first port in communication with the first cylinder and a second port in communication with the second cylinder. The second member may define a longitudinally extending portion located on a first lateral half of the first member. A first control passage and a second control passage may be defined between the first member and the longitudinally extending portion of the second member. The second member may define a wall separating the first and second control passages from one another.
The first valve may be located in the first port and the second valve may be located in the second port. The first valve lift mechanism may be supported on the cylinder head assembly and engaged with the first valve and in communication with the first control passage. The second valve lift mechanism may be supported on the cylinder head assembly and engaged with the second valve and in communication with the second control passage. The camshaft may be supported on the cylinder head assembly and engaged with the first and second valve lift mechanisms.
Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.
The drawings described herein are for illustrative purposes only and are not intended to limit the scope of the present disclosure in any way.
Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.
Examples of the present disclosure will now be described more fully with reference to the accompanying drawings. The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses.
Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail.
When an element or layer is referred to as being “on,” “engaged to,” “connected to” or “coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to,” “directly connected to” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.
Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments.
With reference to
A four cylinder engine assembly is illustrated with first and second cylinders 24, 26 described for simplicity. However, it is understood that the present teachings apply to any number of piston-cylinder arrangements and a variety of reciprocating engine configurations including, but not limited to, V-engines, inline engines, and horizontally opposed engines, as well as both overhead cam and cam-in-block configurations.
The cylinder head assembly 22 may include a first member 28 coupled to the engine block 20 and a second member 30 coupled to the first member 28. The first member 28 may define intake and exhaust ports. More specifically, a first port 32 may be in communication with the first cylinder 24 (
The second member 30 may include a first side 48 abutting the first member 28 and facing the engine block 20 and a second side 50 opposite the first side 48. The second side 50 may define a camshaft support surface including cam bearing regions 52. The second member 30 may include a monolithic body defining eight oil supply regions 54, 56, 58, 60, 62, 64, 66, 68 (one for each pair of intake valves and one for each pair of exhaust valves for each cylinder) isolated from one another by walls 70, 72, 74, 76, 78, 80.
The monolithic body may form first and second longitudinally extending portions 31, 33 with cross-members 35 extending laterally between the first and second longitudinally extending portions 31, 33 at the cam bearing regions 52. The first longitudinally extending portion 31 may be located on a first lateral half of the first member 28 of the cylinder head assembly 22 and may define four of the oil supply regions 54, 56, 58, 60 for an intake side of the cylinder head assembly 22. The second longitudinally extending portion 33 may be located on a second lateral half of the first member 28 of the cylinder head assembly 22 and may define four of the oil supply regions 62, 64, 66, 68 for an exhaust side of the cylinder head assembly 22. First and second oil supply regions 54, 56 will be described for simplicity with the understanding that the description applies equally to the remaining oil supply regions 58, 60, 62, 64, 66, 68.
The first oil supply region 54 may include a first recess 82 defined in the first side 48 of the second member 30 and first lash adjuster passages 84. Similarly, the second oil supply region 56 may include a second recess 86 defined in the first side 48 of the second member 30 and second lash adjuster passages 88. A first control passage 92 and a second control passage 94 may be defined between the first and second members 28, 30. The first recess 82 and an adjacent surface of the first member 28 may define the first control passage 92. The second recess 86 and the adjacent surface of the first member 28 may define the second control passage 94. The first and second control passages 92, 94 may be isolated from one another by the wall 70 defined by the second member 30. The combination of the first lash adjuster passage 84 and the opening 44 in the first member 28 may form a first lash adjuster housing 96 and the combination of the second lash adjuster passage 88 and the opening 46 in the second member 30 may form a second lash adjuster housing 98.
The valvetrain assembly 18 will be described relative to one of the ports for each of the first and second cylinders 24, 26 for simplicity. As seen in
The first valve lift mechanism 106 may be supported on the cylinder head assembly 22 and engaged with the first valve 102 and may be in communication with the first control passage 92. Similarly, the second valve lift mechanism 108 may be supported on the cylinder head assembly 22 and engaged with the second valve 104 and may be in communication with the second control passage 94. The first valve lift mechanism 106 may form a first multi-step valve lift mechanism and the second valve lift mechanism 108 may form a second multi-step valve lift mechanism.
In the present non-limiting example, the first lash adjuster 110 is located in the first lash adjuster housing 96 and the second lash adjuster 112 is located in the second lash adjuster housing 98. The first valve lift mechanism 106 may be supported on the first lash adjuster 110 and in communication with the first control passage 92 via the first lash adjuster 110 and the second valve lift mechanism 108 may be supported on the second lash adjuster 112 and in communication with the second control passage 94 via the second lash adjuster 112, as discussed below. The first and second valve lift mechanisms 106, 108 and the first and second lash adjusters 110, 112 may be similar to one another. Therefore, the first valve lift mechanism 106 and the first lash adjuster 110 will be described with the understanding that the description applies equally to the second valve lift mechanism 108 and the second lash adjuster 112.
With additional reference to
The first valve lift mechanism 106 may be operable in a first lift mode and a second lift mode providing a greater displacement of the first valve 102 than the first lift mode. The second valve lift mechanism 108 may also be operable in the first lift mode and the second lift mode. In a first arrangement, the first and second lift modes may each provide some amount of valve opening. In a second arrangement, the first lift mode may include the first valve 102 being maintained in a closed position when the first lobe member 118 engages the first valve lift mechanism 106. Similarly, the second arrangement may include the second valve 104 being maintained in a closed position when the second lobe member 120 engages the second valve lift mechanism 108.
By way of non-limiting example, the first and second members 114, 116 may be secured for displacement with one another via the locking mechanism during the second lift mode and may be displaceable relative to one another during the first lift mode. The first valve lift mechanism 106 may be switched between the first lift mode and the second lift mode by pressurized fluid provided by the first control passage 92 via the first lash adjuster 110. Similarly, the second valve lift mechanism 108 may be switched between the first lift mode and the second lift mode by pressurized fluid provided by the second control passage 94 via the second lash adjuster 112.
As seen in
The inner member 130 may define an oil passage 134 in communication with the first control passage 92 and the first valve lift mechanism 106 to provide for actuation of the first valve lift mechanism 106 between the first and second lift modes. During operation, the first and second valve mechanisms 106, 108 may be switched between the first and second lift modes independent from one another due to the isolation of the first and second control passages 92, 94 from one another provided by the wall 70.
An alternate arrangement is illustrated in
